Macromolecular hydrogels for the colorimetric detection and efficient separation of cobalt (II) in complex aqueous media

Abstract

Azobenzene quinolinol–based hydrogels were developed for the highly selective detection and separation of Co(II) ions in complex aqueous media. (E)-2-((4-(Diazenyl(8-hydroxyquinolin-5-yl))phenyl)(methyl)amino)ethyl acrylate (DHPMAA) and N,N-dimethylacrylamide (DMA) were copolymerized to yield p(DMA-co-DHPMAA). The polymeric probe exhibited high selectivity and sensitivity toward Co(II) ions in aqueous solutions. Hydrogels based on p(DMA-co-DHPMAA) were synthesized via photopolymerization and were demonstrated to effectively separate Co(II) ions from various other metal ions. The selectivity was further demonstrated under challenging conditions in which the concentration of Fe(II) ions substantially exceeded that of Co(II) ions, simulating radioactive waste in cooling channels of nuclear power plants. The synthesized hydrogels were able to selectively separate Co(II) ions from a complex mixture containing excess Fe(II) ions at a concentration five times that of the Co(II) ions, demonstrating the application potential of the hydrogels for Co(II) ions removal.